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Published online by Cambridge University Press: 26 February 2011
We report a detailed study using photoluminescence and photoluminescence excitation of MOCVD GaAs grown directly on Si substrates. Temperature variation and selective excitation allow reliable assignment of spectral features. This assignment permits measurements of strain and strain uniformity, identification of impurities, and assessment of general materials quality. In 2–5μm thick layers similar spectra are observed with little variation from substrate character. Most samples show one of the two split valence band features plus defect recombination, always including carbon. Strain uniformity varies widely and correlates with substrate thickness. The range of spectra observed from a variety of samples, and guidelines for interpretation of nonresonantly excited spectra will be discussed.